1. Field of the Invention
The present invention relates to a controller of an AC generator for a vehicle, particularly, a controller of an AC generator for a vehicle in which a malfunction of a charging wire or a battery voltage detecting line can be efficiently detected.
2. Description of the Related Art
Up to now, as the above kind of controller of an AC generator for a vehicle, provided having been a controller of an AC generator for a vehicle, the controller capable of well controlling electric generation in accordance with an electric generation voltage or a battery voltage even in the case of disconnection of the generator output line (a battery charging wire). For example, a battery voltage and an output voltage of an electric generator are separately detected to usually put priority on detecting the battery voltage for controlling electric generation, on one hand. On the other hand, the output voltage of the generator is detected to control electric generation in the case of disconnection of the output voltage of the generator while a voltage is adjusted in accordance with the battery voltage when the battery voltage detecting line is disconnected so that each driver can be informed of the respective cases. (Refer to Patent Reference 1, for example.)
Patent Reference 1 is JP-A-S57-148541.
In the above-mentioned conventional technology, however, many comparators are required for detecting that the battery voltage has decreased to a predetermined voltage due to an electric discharge. This causes necessity of forming a complicated logic circuit for carrying out predetermined control of electric generation. The complicated logic circuit causes an IC circuit to be complicated and the area of the IC chip to be increased. Further, it causes a rise in cost since the area of the IC chip is directly reflected in a cost.
Moreover, increase in resistance due to electrolytic corrosion of wiring and the like is considerable as one of malfunction modes around the generator. Influence of the above causes a rise in controlling voltage of the generator and is likely to cause serious problems of a battery or other electronics. In the technology up to now, however, it takes long time to detect a malfunction mode since the battery voltage cannot be detected until it reaches a certain threshold value Vth or less.